The modified aircraft known as the Douglas World Cruiser (DWC), also was the first major project for Jack Northrop who designed the fuel system for the series.[6] After the prototype was delivered in November 1923, upon the successful completion of tests on 19 November, the Army commissioned Douglas to build four production series aircraft.[7] Due to the demanding expedition ahead, spare parts, including 15 extra Liberty L-12 engines, 14 extra sets of pontoons, and enough replacement airframe parts for two more aircraft were chosen. These were sent to airports along the route. The last of these aircraft was delivered to the U.S. Army on 11 March 1924.[4]

After the success of the World Cruiser, the Army Air Service ordered six similar aircraft as observation aircraft.[8][8][9] The success of the DWC established the Douglas Aircraft Company among the major aircraft companies of the world and led it to adopt the motto "First Around the World - First the World Around".[10]

The company is most famous for the "DC" ("Douglas Commercial") series of commercial aircraft, including what is often regarded as the most significant transport aircraft ever made: the Douglas DC-3, which was also produced as a military transport known as the C-47 Skytrain or "Dakota" in British service. Many Douglas aircraft had long service lives.

Douglas Aircraft designed and built a wide variety of aircraft for the U.S. military, including the Navy, Army Air Forces, Marine Corps, Air Force, and Coast Guard.

Machine tool operator at the Douglas Aircraft plant, Long Beach, California in World War II. After losing thousands of workers to military service, American manufacturers hired women for production positions, to the point where the typical aircraft plant's workforce was 40% female.[14]

World War II was a major boost for Douglas. Douglas ranked fifth among United States corporations in the value of wartime production contracts.[15] The company produced almost 30,000 aircraft from 1942 to 1945, and its workforce swelled to 160,000. The company produced a number of aircraft including the C-47 Skytrain, the DB-7 (known as the A-20, Havoc or Boston), the SBD Dauntlessdive bomber, and the A-26 Invader.[16][17][18]

Douglas Aircraft suffered cutbacks at the end of the war, with an end to government aircraft orders and a surplus of aircraft. It was necessary to cut heavily into its workforce, letting go nearly 100,000 workers.

The United States Army Air Forces established 'Project RAND' (Research ANd Development)[19] with the objective of looking into long-range planning of future weapons.[20] In March 1946, Douglas Aircraft Company was granted the contract to research on intercontinental warfare.[20] Project RAND later become the RAND Corporation.

Douglas continued to develop new aircraft, including the successful four-engined Douglas DC-6 (1946) and its last propeller-driven commercial aircraft, the Douglas DC-7 (1953). The company had moved into jet propulsion, producing its first for the U.S. Navy — the straight-winged F3D Skyknight in 1948 and then the more "jet age" style F4D Skyray in 1951. Douglas also made commercial jets, producing the Douglas DC-8 in 1958 to compete with the new Boeing 707.

In 1967, the company was struggling to expand production to meet demand for DC-8 and DC-9 airliners and the A-4 Skyhawk military attack aircraft. Quality and cash flow problems and DC-10 development costs, combined with shortages due to the Vietnam War, led Douglas to agree to a merger with McDonnell Aircraft Corporation to form McDonnell Douglas. Douglas Aircraft Company continued as a wholly owned subsidiary of McDonnell Douglas, but its space and missiles division became part of a new subsidiary called McDonnell Douglas Astronautics Company.

McDonnell Douglas later merged with its rival Boeing in 1997.[21] Boeing combined the Douglas Aircraft Company with the Boeing Commercial Airplanes division, ending more than 75 years of Douglas Aircraft Company history. The last Long Beach-built commercial aircraft, the Boeing 717 (third generation version of the Douglas DC-9), ceased production in May 2006. By 2011, the Boeing C-17 Globemaster III was the last aircraft being assembled at the Long Beach facility; the final C-17 was assembled in late 2015.[22]